Different subject though, but when smoking flower it’s a totally different ballgame than vape because of the temperatures (the product is literally on fire) and also there even more compounds in the starting material.
Pretty sure the majority of actives are likely vaporized by superheated air from the cherry traveling through the joint/bowl ahead of actual combustion of the plant material.
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Maybe I’m confused but what solvents are being found or theorized to be found from terpene vaporization?
From my understanding terpenes themselves are natural solvents, that’s why putting them in high concentrations in cartridges causes irritation to the throat, lungs and sinuses when smoked. They’re at low enough concentrations in flower that it doesn’t bother you as much but when blending a high percentage of an extremely concentrated terpene into some distillate or oil it could cause problems or be dangerous potentially (in theory?) I’m not sure we have enough studies done on the dangers of it all, but in the end consuming a vaporized solvent can’t be that great for you at high concentrations, but damn does it give some flavors lol
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Abstract
A mechanism is proposed for the formation of acetone in the OH-initiated atmospheric oxidation of α-pinene. In a first step, addition of the OH radical onto the α-pinene double bond forms a chemically activated tertiary radical P1OH†. This activated radical can then for a certain fraction break its four-membered ring, leading to a 6-hydroxymenthen-8-yl radical, which is subsequently converted to a 6-hydroxymenthen-8-oxy radical by reaction with O2 and NO, and elimination of an NO2 molecule. Finally, the 6-hydroxymenthen-8-oxy radical forms acetone by β C
C bond rupture. For each of these steps, competing reactions are considered, as well as the site and stereospecificity of the reaction itself. To quantify the acetone yield, quantum chemical calculations were combined with RRKM-Master Equation analyses for most of the reactions; other branching ratios were estimated from available literature data. The total yield of acetone was obtained by propagating the relevant product fractions of each step in the mechanism. We find an acetone yield of 8.5%, in good agreement with available experimental data. The uncertainty interval is estimated at 4−16%. It should be emphasized that only the nascent, chemically activated P1OH† radicals contribute to the crucial ring-breaking isomerization step.
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Pinene can break down into acetone, but it’s stable af compared to terpinolene and ocimenes.
You can have unstable terpenes break down under normal storage conditions or stable ones that break down as a function of the technique of analysis used to measure them.
There’s a lot of misidentified compounds that could easily appear as common solvents when you don’t have the correct standards/libraries to reference. Everyone tests for acetone, hexane, etc so naturally you’re going to get a lot of results that have a bias towards something being a common solvent. It’s not until you have access to more sensitive testing methods that you’ll see that not everything is as it seems.
There are without a doubt a ton of degradation products. They’re not “solvents” like those that are tested for in compliance testing (though technically still solvents by definition, and some are solvents in other industrial processes).
Terpinolene forms dozens of unnamed monoterpenoids/alkenes that could easily be mistaken as a known solvent. Several of which are low MW dienes that structurally resemble terpinene. This is especially true if the material warms up during live extraction/fresh frozen before it’s distilled.
Limonene is definitely not very “stable”, it just doesn’t degrade in the same way we’d think. Limonene readily degrades to para-Cymene and Carveol. Both being common and easily identifiable terpenes, you wouldn’t assume it’s from limonene degrading.
Myrcene also is much more ambiguous in how it degrades. Instead of forming a slew of unnamed monoterpenoids like terpinolene, it undergoes an addition reaction known as dimerization where two myrcene molecules join together to form a much heavier compound. This would easily go unnoticed because a) no one tests for this normally and b) it elutes so much later than anything else in your terpene sample. This is why myrcene isolate and myrcene-dominant hemp terpenes get so thick if stored improperly. I’ve said before that these types of byproducts in relation to their counterparts will directly correlate to the age of cannabis terpenes. The only exception to this is when they’re kept frozen and under perfect storage conditions.
To add to that, pinene actually can degrade into myrcene while also forming other extremely low molecular weight byproducts that again could be very easily misidentified as common solvents (cyclohexene/cyclobutene isomers). The main source of myrcene is actually made from the conversion of pinene.
Overall I’d say that the majority of the test results saying they identified a solvent in terpenes are a simple lab error. Testing a terpene sample is much less cut and dry for cannabis/hemp testing labs so you’re going to see a lot more inconsistent results if you shop around on labs. As for things like acetone, toluene, and hexane, I stand by the fact I’ve never once seen those solvents show up outside of a situation where that processor admitted to handling those solvents in the same facility. Considering that all 3 of those are staples in many hemp labs, I’d say if it looks like a duck, quacks like a duck, then it’s probably a duck. Or an isomer of a duck that you didn’t look for.
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What a write up! Thank you so much for all the great information, gives me a bit to chew on and consider. I think as terpene farming continues to grow in popularity labs will get better at analyzing them without misidentifying compounds. It seems like something in the industry that is still in it’s infancy unfortunately, but it’s gaining a lot more interest and attention which will hopefully lead to more studies to better understand the risks involved.
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